DateDiff
Gets the difference of two dates measured by a specified interval
Declare Function DateDiff ( ByRef interval As Const String, ByVal serial1 As Double, ByVal serial2 As Double, ByVal firstdayofweek As Long = fbUseSystem, ByVal firstdayofyear As Long = fbUseSystem ) As Long
#include "vbcompat.bi"
result = DateDiff( interval, date_serial1, date_serial2 [, firstdayofWeek [, firstweekofyear ] ] )
interval
Returns an integer corresponding to the number of intervals found between two Date Serials.
If date_serial1 > date_serial2, the result is negative.
interval is specified as follows:
first_dayofweek Affects the counting when 'ww' interval is used.
first_weekofyear specifies which year (previous or next) that the week which spans the end of one year and the beginning of the next should included with.
Notice if you do an arithmetical subtraction of two date serials you get the difference in days.
The compiler will not recognize this function unless vbcompat.bi or datetime.bi is included.
Syntax
Declare Function DateDiff ( ByRef interval As Const String, ByVal serial1 As Double, ByVal serial2 As Double, ByVal firstdayofweek As Long = fbUseSystem, ByVal firstdayofyear As Long = fbUseSystem ) As Long
Usage
#include "vbcompat.bi"
result = DateDiff( interval, date_serial1, date_serial2 [, firstdayofWeek [, firstweekofyear ] ] )
Parameters
interval
the unit of time (interval) with which to measure the difference
date_serial1starting date serial
date_serial2end date serial
firstdayofweekfirst day of the week
firstdayofyearfirst day of the year
Return Value
Returns an integer corresponding to the number of intervals found between two Date Serials.
If date_serial1 > date_serial2, the result is negative.
Description
interval is specified as follows:
| value | interval |
| yyyy | years |
| q | quarter(three months) |
| m | months |
| w | seven day periods |
| ww | calendar weeks |
| d,y | days |
| h | hours |
| n | minutes |
| s | seconds |
| value | first day of week | constant |
| omitted | sunday | |
| 0 | local settings | fbUseSystem |
| 1 | sunday | fbSunday |
| 2 | monday | fbMonday |
| 3 | tuesday | fbTuesday |
| 4 | wednesday | fbWednesday |
| 5 | thursday | fbThursday |
| 6 | friday | fbFriday |
| 7 | saturday | fbSaturday |
| value | first week of year | constant |
| 0 | local settings | fbUseSystem |
| 1 | January 1's week | fbFirstJan1 |
| 2 | first weeks having 4 days in the year | fbFirstFourDays |
| 3 | first full week of year | fbFirstFullWeek |
The compiler will not recognize this function unless vbcompat.bi or datetime.bi is included.
Example
#include "vbcompat.bi"
Dim s As String, d1 As Double, d2 As Double
Line Input "Enter your birthday: ", s
If IsDate( s ) Then
d1 = DateValue( s )
d2 = Now()
Print "You are " & DateDiff( "yyyy", d1, d2 ) & " years old."
Print "You are " & DateDiff( "d", d1, d2 ) & " days old."
Print "You are " & DateDiff( "s", d1, d2 ) & " seconds old."
Else
Print "Invalid date"
End If
Dim s As String, d1 As Double, d2 As Double
Line Input "Enter your birthday: ", s
If IsDate( s ) Then
d1 = DateValue( s )
d2 = Now()
Print "You are " & DateDiff( "yyyy", d1, d2 ) & " years old."
Print "You are " & DateDiff( "d", d1, d2 ) & " days old."
Print "You are " & DateDiff( "s", d1, d2 ) & " seconds old."
Else
Print "Invalid date"
End If
Differences from QB
- Did not exist in QB. This function appeared in Visual Basic.
See also